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I would like peoples opinion on a competition i have soon. Its a hill climb, 20% gradient 0.1miles, nothing long but short and sharp. I should be able to complete at around 15secs at 20mph on my cosmic slr's. Does anyone think i would gain any advantage with c24's for this climb over my slr's?

Last edited by Andyvenge on Mon Apr 28, 2014 12:36 am, edited 1 time in total.

The C24 would likely be faster but, the amount is academic. The event timer won't have the measurement resolution tolerance to record a reliable result. Instead, focus on minimizing total weight (that includes yourself). That will be within the timer accuracy tolerance.

Interesting. Now consider the following scenario, which perhaps led me astray.

Case A) Assume 4 riders all with the same power output and aero losses when riding by themselves. Have them ride 2 across and 2 deep, so the same scenario as tested by the magazine, but with each lead rider having someone behind.

Case B) Same as case A, except there are only 2 riders, with one in front of the other.

I thought that case A should be faster than case B. And a case with 3 across, each with a lead and follower should be even faster. Is that correct?

No, I don't believe so. The net drag of 2 riders side by side is slightly more than double the net drag of 1 rider, and I don't see why it would be different in a double row.

And the side by side thing is not just a theoretical effect, or one that only shows up under controlled circumstances in a wind tunnel, it is absolutely a verifiable real world effect. It's not news to me because it's something I've known about from a skydiving background. When planning large formation skydives it has to be taken into account that the more people join a set style of formation, the slower it's going to fall. For real.

I would like peoples opinion on a competition i have soon. Its a hill climb, 20% gradient 0.1miles, nothing long but short and sharp. I should be able to complete at around 15secs at 20mph on my cosmic slr's. Does anyone think i would gain any advantage with c24's for this climb over my slr's?

Does that mean it's a flying start? If so I'd say you'd be better off with the most aero setup possible.

Here's an excellent article on the effect of rim weight vs aerodynamics: http://alex-cycle.blogspot.com/2014/12/ ... ts-ii.htmlBasically, even for worst case scenarios like standing start and rolling accelleration (i.e out of a corner in a crit) the heavier aero rim wheels win.

Good blog with the exception that the aero wheel drag number is only applicable in a narrow range of yaw. I would have preferred to see the result with zero existing wind conditions as a baseline (which means a head-on wind the tires start rolling). For time trial riding, and perhaps for people that do lots of group "pulling", the aero wheel makes sense. The truth is that it doesn't take much more energy to spin it up. But these wheels come with disadvantages too - like cost, carbon brake tracks, cross wind susceptibility, etc. Anyone that can beat me on a pair of high zoot aero wheels will also beat me on a pair of cheap box rim clinches. For now, I'll stick with my tried and true, and imminently dependable DA C24's. I've yet to ride a wheel that I liked better. But if you want deep dish aero wheels, nothing wrong with them either outside the typical drawbacks.

I have to choose for a TT in Feb that is 6 miles North and back where there are typically 5 mph side winds. The course climbs 90m (270ft) in that 6 miles.Most riders come back 2-3k faster than they went out.

My dilemma is go with a traditional 90mm profile that is 200g heavier per wheel or use 55m profiles that are lighter. The yaw will likely work out to about 10 degrees.

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